you have to distribute it or use FOIL (if u know that method). This is basically factoring. for instance: (2x-9)×(x+4) first: 2x × x = 2x^2 second: 2x × 4 = 8x third: -9 × x = -9x forth: -9 × 4 = -36
now combine like terms. 2x^2 + 8x -9x - 36 (8x and -9x are like terms) (add the two together, which is -1x or -x) 2x^2 -x -36 is ur answer
